1. Field of the Invention
This invention relates to a drive for rotating a wheel and, in particular, to a hub drive for rotating a wheel.
2. Description of the Related Art
Wheeled ground vehicles have been used for many years to carry personnel, cargo, and other equipment. Such vehicles generally have some means of producing a motive force to the wheels, such as an engine or motor in combination with a drive train. For example, in a rear-wheel drive automobile, an engine generates the motive force for propelling the automobile and the drive train includes a transmission, drive shaft, differential, and driven axles. The transmission, which is rotationally coupled with the engine, allows the automobile to be propelled at various speeds. The drive shaft transmits rotary motion from the transmission to the differential, which couples the drive shaft and the driven axles. The driven axles are attached to the driven wheels and, thus, are supplied with the motive force from the engine.
Such systems used to provide a motive force to wheels of ground vehicles are often large, heavy and complex. In applications wherein it is desirable for some or all of the wheels to be capable of being driven independently (i.e., at different speeds), the complexity and size of the motive force system may increase dramatically. For example, in vehicles with a single engine or motor, a transmission may be required for each of the wheels if they are to be capable of being driven independently. Such complex systems often are difficult to install and maintain and may be prone to failure merely due to their complexity. Conventional systems may also limit the types of suspensions possible for the vehicle, due to difficulties encountered in routing power transmitting elements therethrough.
Further, conventional vehicles often experience a jolt or hesitation during transmission shifting, which may be undesirable depending upon the use of the vehicle. For example, if the vehicle is being used to transport a gun or the like, such jolting or hesitation may decrease the accuracy of the gun, if it is fired while the vehicle is being operated.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.